Dave Martindale wrote:
Nate Nagel writes:


As an aside, the old dehumidifier just had the little rotating knob
humidistat on it and I'd set it for slightly higher than "normal"
humidity. It cycled on and off, more off than on. The new one has a
digital humidistat so I set it for 55% RH because I've heard that to
minimize all of the bad things that can happen to your basement due to
incorrect humidity you should be in the 45-55% range. Apparently the
old dehumidifier was actually set for about 60 to 65% RH. New unit
showed 65% when I turned it on, quickly dropped to 60, now is showing
55% but have not heard it shut off yet (granted, I haven't been in my
basement for the whole time period.)


Leave it alone for a day or two, then see if it's still running
constantly. If your old dehumidifier was set to 65%, then *everything*
in your basement that can absorb water vapour has about that level of
absorbed water. If you try to bring the humidity down to 55%,
everything is going to be "bleeding" moisture into the air for a while -
your drywall and studs, your bookshelfs, all the books, etc. Once the
humidity has been 55% for a while, everything else will stabilize at
that level, and the dehumidifier will have to run less.

Follow up - I think you were correct. It's taken a couple of days, but
it finally started cycling at 55%. I kicked it down to 50% last night,
now it's running more or less constantly again, but definitely
stabilized. I wish I had a good hygrometer to measure the humidity
upstairs so I'd know if I was trying to fight the whole house or not.
Might have to pick one of those up.

As an aside, I was mistaken about the new LG dehumidifiers - the fan
runs when you first plug them in, but after three minutes or so it
either kicks in the compressor and/or shuts off, depending on humidity.
If the compressor then cycles off, the fan shuts off too, as one would
expect. This is in contrast to the Frigidaire model I tried first - the
fan on that would run constantly no matter what, and it would not
recover correctly from a power failure.

I still am not 100% satisfied with the LG's - when recovering from a
power failure, if the power has been out for more than a few seconds,
the dehumidifier will revert to "on" mode rather than whatever humidity
selection you'd set on it. So it should probably be unplugged in the
wintertime, when dehumidification is not required or desirable. Also I
suspect that the one in the garage might have an issue with the
humidistat - twice now I've found it running but the ambient humidity
displayed is lower than the setpoint. (the garage seems to have
stabilized far quicker than the basement for some reason, even though
it's nearly as large, and was far more humid - this was the initial
impetus to go out and buy a new humidifier in the first place.)

I'm just posting this more for the benefit of anyone shopping for a
dehumidifier, so they don't have to go through the process of making an
expensive purchase, getting it home, and finding that it doesn't suit
their needs at all, like I did...

So I assume that it just displays
in 5% increments and showing 55% means it's probably in the range of
52.5-57.5%. This is a 45 pint unit and based on the amount of water
it's pulled out, I don't know that I suspect that there's a problem with
the unit; more that my house is very open and it would seem that due to
the climate (this AM: almost 90 degrees and 57% RH outside; now, 77
degrees and raining) the humidity in the whole house is higher than 55%
and trying to suck it down to that is taxing the unit. Any real problem
just leaving it at 60% and letting it go, even if that isn't "ideal?"


If outside air can flow freely through your house, you are trying to
dehumidify the outdoors. That is a hopeless task. You need to provide
some barrier between inside and outside air.

On the other hand, it's not "taxing" your unit to run all the time; it
oought to be built to deal with that. At worst, it won't be able to
keep the humidity down to what you want.

It's a house built in 1948... I'm sure it's not as airtight as it could
be, although the windows and doors have been upgraded over the years.
The windows in the basement are still the originals; I'd like to get
those replaced in the near future, soon as I come up with some cash in
the home improvement fund.

nate

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